1. Field of the Invention
This invention relates to reverse-Galilean finders, and more particularly to reverse-Galilean finders capable of changing the magnification (magnifying power).
2. Description of the Prior Art
Previously known varifocal type reverse-Galilean finders are generally constructed with, from front to rear, a lens of positive refractive power and another lens of negative refractive power constituting an objective lens having a negative refractive power as a whole followed by an eyepiece of positive refractive power. When the lens of negative refractive power in the objective lens is interchanged by another lens of different negative refractive power, the magnification is changed.
In a varifocal type reverse-Galilean finder of such construction, however, when the same ratio of the magnification as that of change of the magnification of the photographic lens is given to the finder, the diameter of the objective lens of the finder becomes necessarily large. This is objectionable in cameras in which the size must be minimized.
An object of the present invention is to minimize the size of the variable magnification type finder.
Another object is to provide a reverse-Galilean finder comprising, from front to rear, an objective lens of negative refractive power and an eyepiece of positive refractive power, wherein the auxiliary lens has a refractive power which satisfies the following condition: EQU mF&lt;mL
where mL is the ratio of change of the magnification of the photographic lens and mF is the ratio of change of the magnification of the finder. The auxiliary lens is attached in a space between the objective lens and the eyepiece, while the size of the viewfield frame of the finder is simultaneously changed so that the percentages of the visual field of the finder in the wide angle and telephoto positions are the same.